Single- and double-width printing groups are generally known, and are typically printing groups whose cylinder width is of such dimensions that the cylinders are capable of supporting two or four printing plates side-by-side. If a printing press, with a single-width printing stage, is employed for imprinting a broadsheet product, the imprinted continuous web is then longitudinally folded in the former of the folding apparatus and is subsequently cut into signatures. It is also possible to imprint tabloid products, if a longitudinal cutting device, which severs the imprinted web linearly in the center, is provided between the printing stage and the folding apparatus. In this case, two partial webs are placed on top of each other in the former, are then cut into sections, and a signature is formed only in the course of subsequent transverse folding of the cut-off sections. The change between tabloid and broadsheet production is comparatively simple, even if webs of different widths are being used in both productions. If the webs are conducted through the printing press, and are centered in relation to a center line, the longitudinal cutting device and the nose of the former are always correctly positioned with respect to each other.
Double-width printing stages are capable of imprinting four printed pages positioned side-by-side, which four printed pages are distributed over the width of a web. Before such a double-width web passes through a turning and mixing stage, it must be cut longitudinally at least once, at the center of the web, for forming two partial webs, each of which has a width of two pages. After mixing and, if required, turning, these partial webs are then conducted to formers of a folding apparatus. If such a press is to be capable of processing webs of different widths, it is either necessary to be able to match the position of the formers to the width of the web or, if the former is fixed, the turning and mixing stage must be capable of laterally offsetting the two partial webs by a fraction of their width in such a way that they arrive correctly centered at the formers and the longitudinal fold is thus formed in the right position. If broadsheet products with inserts, or tabloid products, are formed, the partial webs, provided by the first longitudinal cutting device, must be cut again by two longitudinal cutting devices. With changes in the width of the webs, this longitudinal cutting is only correctly possible if at least the second longitudinal cutting devices can be shifted transversely in relation to the web.
Initially, these problems make it appear that it would be sensible to employ printing presses of single width for printing jobs requiring the use of webs of different widths. However, this has the disadvantage that a number of single-width printing groups, which would be required for producing a signature of a given amount of pages, is twice as large as a number of double-width printing groups which would be needed for the same purpose. Two single-width printing groups are clearly more expensive to construct and are therefore also greater in price than a double-width printing group. Added to this is the fact that commercially available double-width printing groups are often constructed for higher web speeds than are single-width printing groups. To construct a single-width printing press of large output capabilities, it is not possible to utilize existing components. Instead, it is necessary to construct such printing groups from scratch.
DE 197 28 207 A1 discloses a printing press with two turning towers which are arranged between two printing towers, which two turning towers redirect the webs, which run transversely, with respect to the cylinder axes of the printing groups, longitudinally in respect to the cylinder axes. The turning towers conduct the webs to a folding apparatus, in which the formers are arranged transversely, with respect to the cylinder axes.
DE 44 19 217 A1 shows a printing press with a longitudinal former. The width of the longitudinal former is approximately that of the width of the printing groups.
It has become known, for example from an article by Engelbert Muth in Polygraph 1965, pages 508 to 512, and entitled “Falzvorrichtungen an Rollentiefdruckmaschinen” [Folding Devices in Web-Fed Rotogravure Printing Presses], to laterally adjust paper webs by shifting turning bars.
The article by Wolfgang Walenski “Der Falzaufbau (Überbau)”, or [Folding Structure (Superstructure], in “Der Rollenoffsetdruck”, or [Web-Fed Offset Printing], 1st. ed., Fellbach Fachschriften, publishers, 1995, pages 186 to 197, discloses different methods of web guidance to formers by the use of turning bars. For example, on page 194 of the article it is shown to cut a web into two partial webs, to place these partial webs on top of each other and to conduct them centered to a former.
U.S. Pat. No. 3,734,487 discloses displaceable turning bars.
DE 101 31 976 A1 discloses printing presses for variable web widths with a straight path of the webs and with several formers side-by-side.